body {
  margin: 0;
}

div {
  display: flex;
  flex-direction: column;
}

.blank-cell-group,
.char-cell-group {
  width: 100%;
  flex-direction: row;
}

.char-cell-group {
  margin-top: 4rem;
  flex-wrap: wrap;
}

.blank-cell-group .cell-item,
.char-cell-group .cell-item {
  width: 25%;
  /* height: 25vw; 相当于宽度的25% */
  height: 25vw;
  padding: 0.5rem;

  box-sizing: border-box;
}

.blank-cell-group .cell-item .wrapper,
.char-cell-group .cell-item .wrapper {
  width: 100%;
  height: 100%;
  border: 1px solid #ddd;
  border-radius: 0.5rem;
  box-sizing: border-box;
}

.char-cell-group .cell-item .wrapper {
  border: none;
  background-color: lightgreen;
  font-size: 3rem;
  justify-content: center;
  align-items: center;
  color: #fff;
  /* transition: all 0.5s ease; */
}
